7.2.0-alpha.1 I2C issues when scanning the bus

[UnexpectedMaker]

CircuitPython version

Adafruit CircuitPython 7.2.0-alpha.1-189-g9a353a4f5-dirty on 2022-01-22; TinyS2 with ESP32S2
But really on any ESP32 board. S2 and S3.

Code/REPL

import board
import busio
i2c = busio.I2C(board.SCL, board.SDA)
while not i2c.try_lock():
    pass
    
[hex(x) for x in i2c.scan()]

Behavior

Scan hangs for 60-90 seconds, and then comes back with nothing found.
Confirmed on my TinyS2, TinyS3, FeatherS3 and corroborated with @prplz using the esp32s3 devkitc n8r8

Description

No response

Additional information

No response

[UnexpectedMaker]

Ok, if the slave has pull-ups.... it seems to work, if multiple slaves connected and one has pull-ups, it works and finds them all, but if the one with pull-ups is removed, the next scan long hangs again.

If a slave with no pull-ups is connected and nothing else, it long hangs.

Only once I've see the "no pull-ups error".... every other time it hangs. I've plugged in and unplugged 4 different I2C modules, some with and some without pull-ups, I can't make sense out of what is happening.

[prplz]

I did a little printf debugging and found that this for loop is taking about one second per iteration

This makes sense because i2c_master_cmd_begin is being called with a 10 tick timeout and we are using 100Hz FreeRTOS tick rate.

[dhalbert]

@prplz @UnexpectedMaker This was closed by #5958, and I reduced a timeout, but reopen or make a new issue if you are still seeing slow scan times, and we need something like #5908 (or comment in that PR).